If the C&R rifle is 50 or more years old, it can legally be transferred via face-to-face cash & carry.
Meaning, if they are a non-prohibited person, then they give you money and you hand them the firearm.
Checking to see if they are a non-prohibited person is, most often, accomplished by checking their CA DL/ID, in order to verify they are over 18 years of age & are a CA resident, and asking them a few questions to check if they are prohibited from possessing firearms/ammunition (are you a felon?, etc).

Some people will do a bill-of-sale to document that the transfer took place, but it is not required by Federal or CA state laws.

Some M-1 Carbines are not C&R and do not qualify for this type of transfer.
So, make sure your M-1 Carbine is a C&R that is 50 or more years old.

Penal Code 27965
(a) If all of the following requirements are satisfied, Section 27545 does not apply to the sale, loan, or transfer of a firearm:
(1) The sale, loan, or transfer is infrequent, as defined in Section 16730.
(2) The firearm is not a handgun.
(3) The firearm is a curio or relic manufactured at least 50 years prior to the current date but is not a replica, as defined in Section 478.11 of Title 27 of the Code of Federal Regulations, or its successor.
(b) This section shall remain in effect only until January 1, 2014, and as of that date is repealed, unless a later enacted statute, that is enacted before January 1, 2014, deletes or extends that date.

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"If someone has a gun and is trying to kill you, it would be reasonable to shoot back with your own gun.” - Dalai Lama (Seattle Times, 05-15-2001).